Nigeria said Wednesday it will boost security at camps for refugees driven from their homes by violence, after two female suicide bombers killed at least 58 at a camp in Dikwa.

It is "regrettable that the heartless terrorists chose to unleash their wickedness on people who were taking refuge from previous acts of destruction in their homes," said Vice President Yemi Osinbajo.

He promised the government will place "formidable security" around camps for internally displaced people.

Officials say three female suicide bombers disguised themselves as refugees and entered the camp. Two blew themselves up. The third changed her mind and surrendered to police when she discovered her parents and siblings were living there.

The attack was carried out late Tuesday, but not reported until Wednesday because of poor communications.

Dikwa is about 85 kilometers north of Maiduguri, the capital of Borno state.

No one has claimed responsibility, but suspicion immediately fell on Boko Haram — the Islamist extremists behind much of the violence that forced more than 2 million people from their homes during its insurgency in Nigeria, Cameroon, Chad and Niger, aimed at setting up an Islamic caliphate.